Battle of Hastings
The Battle of Hastings took place on the 14th of October, 1066, when the defending English army, also called the Anglo-Saxon army, led by King Harold, engaged invading French on Senlac Hill near Hastings, England. The French won decisively and Harold was killed, effectively ending Anglo-Saxon rule of England and establishing the Norman line of monarchs. The effect on English society was enormous. Among other things, the language itself changed as the influence of French changed Old English into Middle English.
The battle was fought to assert a French claim to the throne. Following the death of Edward the Confessor, William, Duke of Normandy (later William I, also known as William the Conqueror) asserted a claim to the English throne.
The battle was memorialised in the Bayeux Tapestry.